We propose to examine the effects of five months of treatment with GEREF vs. placebo on the sleep quality, 24-hour secretory pattern of growth hormone, and insulin-like growth factor-1 concentrations of three groups of healthy older subjects: men, women not on estrogen replacement therapy and women on estrogen replacement therapy. The inclusion of women on ERT as a separate group is important because estrogen interacts in numerous ways wiht the GH-IGF-1 axis and because an increasing proportion of older women are on chronic ERT.